A conventional scroll control device detects a line-of-sight position of a viewer on a display image, and performs a scroll process when the line-of-sight position of the viewer has reached an end of the display image (refer to Patent Literature 1, for example).
Hereinafter, the conventional scroll control device will be described with reference to drawings.
FIG. 19 is a block diagram showing the configuration of the conventional scroll control device described in Patent Literature 1.
In the conventional scroll control device 110, a display unit 116 for displaying a predetermined document is composed of a monitor such as a CRT (Cathode Ray Tube) or an LCD (Liquid Crystal Display). A document memory 112 stores therein document information to be displayed on the display unit 116. A movement amount detection unit 114 detects an amount of movement of a line of sight on a display image, and a time measurement processing unit 115 measures a time required for the line of sight to move on the display image. A scroll processing unit 113 for scrolling the display image has a function of scrolling the display image in accordance with scroll control information given from a document edition processing unit 117. In addition, a line-of-sight detection processing unit 111 detects a line of sight of a viewer, based on an image of the viewer taken by a camera.
The operation of the conventional scroll control device 110 configured as described above will be described with reference to FIGS. 19 to 21.
It is assumed that document information of a document to be read is stored in the document memory 112, and the specific content of the document is as shown in FIG. 20. When a viewer is reading this document on the screen, an image of the face of the viewer is input to the line-of-sight detection processing unit 111. The line-of-sight detection processing unit 111 detects the face of the viewer, and thereafter, detects the direction of the line of sight of the viewer. Then, the spatial position of the line of sight is detected based on the detected line-of-sight direction and the spatial coordinate positions of the eyes of the viewer, thereby detecting the position of the line of sight of the viewer on the display unit 116. In this line-of-sight detection, when the line of sight stops for a certain time, it is determined that the line of sight is detected. Therefore, even if the line of sight is directed to the display unit 116, it is not determined that the viewer looks at the display image, unless the line of sight stops for the predetermined time. After the line of sight has been detected, the amount of movement of the line of sight and the time required for the movement are measured as well as the position of the line of sight on the display image, and the movement velocity of the coordinate position of the line of sight on the display image is calculated. When the position of the line of sight has reached the most end of the display image as shown in FIG. 20, the display image is scrolled in accordance with the movement velocity of the line of sight at that time as shown in FIG. 21, thereby providing a scroll control device capable of performing appropriate scroll for the viewer.